Sacramento River

Flows and Fishes in the Sacramento-San Joaquin Delta Research Needs in Support of Adaptive Management

Delta Stewardship Council (Delta Council) | August 15th, 2015

Food Web Fuel Differs Across Habitats and Seasons of a Tidal Freshwater Estuary

Estuaries and Coasts (Springer) | July 11th, 2020

Estuarine food webs are fueled by multiple different primary producers. However, identifying the relative importance of each producer to consumers is difficult, particula

Estuarine food webs are fueled by multiple different primary producers. However, identifying the relative importance of each producer to consumers is difficult, particularly for fishes that utilize multiple food sources due to both their mobility and their generally high trophic levels. Previous studies have documented broad spatial differences in the importance of primary producers to fishes within the Upper San Francisco Estuary, California, including separation between pelagic and littoral food webs. In this study, we evaluated the importance of primary producers to adult fishes in three closely spaced subregions that represented disparate habitat types (a tidal wetland channel, a turbid backwater channel, and a deep open-water channel), each a potential outcome of local restoration projects. Using stable isotope analysis coupled with a Bayesian mixing model, we identified significant differences in primary-producer contribution to fishes and invertebrates across habitats and seasons, especially in the relative contribution of submersed aquatic vegetation and phytoplankton. Most fishes utilized multiple primary producers and showed little segregation between pelagic and littoral food webs among habitats. Availability of primary producers differs seasonally and across multiple spatial scales, helping to buffer environmental variability and thus enhancing food web resilience. Ecosystem restoration may improve with emphasis on restoring a wide variety of primary producers to support consumers.

Food Webs of the Delta, Suisun Bay, and Suisun Marsh: An Update on Current Understanding and Possibilities for Management

University of California, Davis (UC Davis) | October 1st, 2016

This paper reviews recent research findings on food web processes since 2008. It also highlights the idea of a changing baseline with respect to food web function. New re

This paper reviews recent research findings on food web processes since 2008. It also highlights the idea of a changing baseline with respect to food web function. New research indicates that interactions between habitat-specific food webs vary across the current landscape. For example, based on early work in the south Delta, the food web associated with underwater vegetation was thought to provide little support to species of concern; however, data from other regions of the estuary suggest that this conceptual model may not apply across the entire region. Habitat restoration has been proposed as a method of re-establishing historic food web processes to support species of concern. Benefits are likely for species that directly access such restored habitats, but are less clear for pelagic species. Several issues require attention to further improve the knowledge of food webs needed to support effective management, including: (1) synthesis of factors responsible for low pelagic biomass; (2) monitoring and research on effects of harmful algal blooms; (3) broadening the scope of long-term monitoring; (4) determining benefits of tidal wetland restoration to species of concern, including evaluations of interactions of habitat-specific food webs; and (5) interdisciplinary analysis and synthesis. The only certainty is that food webs will continue to change in response to the changes in the physical environment and new species invasions.

Forests and Water in the Sierra Nevada: Sierra Nevada Watershed Ecosystem Enhancement Project

University of California, Merced (UC Merced) | November 21st, 2011

In this white paper on the Sierra Nevada Watershed Ecosystem Enhancement Project (SWEEP), we make the case that upstream management of Sierra Nevada forests can significa

In this white paper on the Sierra Nevada Watershed Ecosystem Enhancement Project (SWEEP), we make the case that upstream management of Sierra Nevada forests can significantly increase the value of downstream water resources by shifting water towards higher value uses and optimizing the timing of runoff. The focus of this paper is on the west-side mixed-conifer forests at elevations of about 1500-3600 m (5000-12,000 ft), which are highly productive owing to the availability of sufficient water, predominance of above-freezing temperatures and presence of other conditions necessary for growth.  California has a Mediterranean climate, with wet winters and dry summers. Precipitation falling as rain on Sierra Nevada forests enters the soil and is partitioned between evapotranspiration and runoff. Much of the rainfall leaves the forest as evapotranspiration, owing to ample water storage in the subsurface and temperatures that allow growth year round. At higher elevations, e.g. above elevations of 1800-2100 m depending on both latitude and microclimate, which are dominated by snow rather than rain, the snowpack provides an important seasonal storage of water that, together with subsurface-water storage, provides the water needed for forest growth over the summer and fall. Forest thinning to reduce vegetation and thus evapotranspiration will result in a higher fraction of precipitation, particularly snowmelt, leaving the mountain forest as runoff. Historically, the unique character of Sierra Nevada forests was defined by its tall trees, relatively mild climate and low forest density. In many areas, current forest densities are much higher than historical values. Forest thinning can also influence the timing of snowmelt and runoff. That is, a less-dense canopy can allow snow to reach the ground rather than be held in the canopy; and strategic spacing of forest openings will limit early season sunlight reaching the forest floor and retard snowmelt.  In this paper we review the forest hydrology literature relevant to management of conifer forests in the Sierra snow zone, as that management affects the timing and amount of snowmelt runoff. In order to understand the conceptual and practical challenges, we summarize the key elements of forest energy budget, with specific reference to the Sierra Nevada, and describe several relevant case studies. Although principles that govern the mountain water cycle are well known and models of water and energy balance are informed by field measurements in some areas, there is a severe knowledge gap that limits quantitative predictions of the effects of forest thinning on Sierra Nevada water and energy cycles. Nevertheless, generalizations from reviews of paired catchment studies carried out elsewhere suggest that Sierra Nevada conifer forests contain ecological attributes with a high potential for water-yield gains. Historical studies of forest harvesting in the Sierra Nevada have shown increases of between 14 and 34% in snow accumulation. Treatments that increase snow accumulation help increase water yield during low flows, when water resources’ economic and ecosystem values are highest.  Preliminary estimates based on average climate information suggest that in the Sierra Nevada, treatments that would reduce forest cover by 40% of maximum levels across a watershed could increase water yields by about 9%. Note that this white paper focused on forest management effects on the water balance. Impacts on wildlife habitat, forest health, and fire behavior were not analyzed. The projections and models reported here are designed to describe the potential for modifying water yield and timing. Before implementation of any strategy, a wider consideration of the consequences on forest structure and function would be necessary.  Because of the potential for water-yield increases and extended snow storage, the SWEEP project has developed a plan to evaluate forest thinning related to water yield in representative headwater catchments in the Sierra Nevada, as a basis for extending these treatments to broader areas of the Sierra Nevada. To that end, we outline an experiment that could be carried out in the Onion Creek Experimental Forest, Tahoe National Forest, Placer County, California that could test silvicultural treatments designed to modify the water balance of mixed-conifer, snow-dominated catchments. The treatments are based on a leaf area index (LAI) approach (O’Hara 1998) to forest management, which is well-suited to water yield and timing objectives. Our initial estimates are that treatments could increase water yield as much as 16% and extend snow storage, i.e. delay snowmelt, by days to weeks. 

Formation and prevention of pipe scale from acid mine drainage at iron Mountain and Leviathan Mines, California, USA

Applied Geochemistry (Elsevier) | April 1st, 2020

Pipelines carrying acid mine drainage (AMD) to treatment plants commonly form pipe scale, an Fe(III)-rich precipitate that forms inside the pipelines and requires periodi

Pipelines carrying acid mine drainage (AMD) to treatment plants commonly form pipe scale, an Fe(III)-rich precipitate that forms inside the pipelines and requires periodic and costly cleanout and maintenance. Pipelines at Iron Mountain Mine (IMM) and Leviathan Mine (LM) in California carry acidic water from mine sources to a treatment plant and have developed pipe scale. Samples of scale and AMD were collected from both mine sites for mineralogical, microbiological, and chemical analysis. The scale mineralogy was primarily schwertmannite with minor amounts of poorly crystalline goethite. Although the bulk composition of the scale was similar along the length of the pipeline at IMM, the number of iron-oxidizing bacteria and concentrations of associated trace elements decreased along the flow path inside the pipeline. Laboratory batch experiments with unfiltered AMD from IMM and LM showed that Fe(II) oxidation was driven by microbial activity when the pH was <5. A remediation strategy of decreasing the pH to <2.2 was tested through geochemical modeling and laboratory experiments. These experiments indicated that scale formation could be prevented by decreasing the pH, which could be achieved at IMM by mixing source waters. However, the presence of Fe(III)-rich scale in a pipeline buffers the pH to higher values that may affect the efficacy of this remedial approach.

Fourth National Climate Assessment Chapter 25: Southwest

U.S. Global Change Research Program | November 23rd, 2018

The Southwest region encompasses diverse ecosystems, cultures, and economies, reflecting a broad range of climateconditions, including the hottest and driest climate in t

The Southwest region encompasses diverse ecosystems, cultures, and economies, reflecting a broad range of climateconditions, including the hottest and driest climate in the United States. Arizona, California, Colorado, New Mexico, Nevada, and Utah occupy one-fifth of U.S. land area, extending across globally unique ecosystems from the Sonoran Desert to the Sierra Nevada to the Pacific Coast. The region is home to 60 million people, with 9 out of 10 living in urban areas and the total population growing 30% faster than the national average. The Nation depends on the region for more than half of its specialty crops such as fruits, nuts, and vegetables. The Southwest also drives the U.S. technology sector, with more than 80% of the country’s technology capitalization located in California. Click here for all chapters of the Fourth National Climate Assessment.

Fourth National Climate Assessment Chapter 3: Water

U.S. Global Change Research Program | November 23rd, 2018

Significant changes in water quantity and quality are evident across the country. These changes, which are expected to persist, present an ongoing risk to coupled human

Significant changes in water quantity and quality are evident across the country. These changes, which are expected to persist, present an ongoing risk to coupled human and natural systems and related ecosystem services. Variable precipitation and rising temperature are intensifying droughts, increasing heavy downpours, and reducing snowpack. Reduced snow-to-rain ratios are leading to significant differences between the timing of water supply and demand. Groundwater depletion is exacerbating drought risk. Surface water quality is declining as water temperature increases and more frequent high-intensity rainfall events mobilize pollutants such as sediments and nutrients. Click here for the text of the full report.

Framework to Coordinate Water Quality Improvement and Wildlife Habitat Conservation to Protect California Streams, Wetlands and Riparian Areas

San Francisco Estuary Institute (SFEI) | February 1st, 2016

The emergence of comparable landscape approaches to wildlife conservation and water quality improvement through federal and California state regulatory and management pr

The emergence of comparable landscape approaches to wildlife conservation and water quality improvement through federal and California state regulatory and management programs provides an opportunity for their coordination to better protect California’s aquatic resources, especially streams, wetlands, and riparian areas. Such coordination is patently desirable. A framework has been developed to help coordinate restoration and compensatory mitigation across policies governing wildlife conservation and water quality in the landscape context. The framework is based on the Wetland and Riparian Area Monitoring Plan (WRAMP) of the California Wetland Monitoring Workgroup (CWMW) of the Water Quality Monitoring Council. The framework presented here is a version of the standard WRAMP framework. It only differs from the standard framework to better accommodate wildlife conservation planning, assessment and reporting. To distinguish this version from the standard version, it is termed theWRAMP for wildlife (WRAMPw).

Franks Tract Futures

Delta Stewardship Council (Delta Council) | April 26th, 2022

Frequently Asked Questions Related to the CASGEM Program

California Department of Water Resources (DWR) | August 21st, 2023

Since 2009, the California Statewide Groundwater Elevation Monitoring (CASGEM) Program has tracked seasonal and long-term groundwater elevation trends in groundwater basi

Since 2009, the California Statewide Groundwater Elevation Monitoring (CASGEM) Program has tracked seasonal and long-term groundwater elevation trends in groundwater basins statewide. The program’s mission is to establish a permanent, locally-managed program of regular and systematic monitoring in all of California's alluvial groundwater basins. Senate Bill x7-6, passed by the legislature in 2009, established collaboration between local monitoring parties and DWR to collect statewide groundwater elevations, to be made available to the public. In response to the law, we developed the CASGEM program. Collecting and evaluating these groundwater data on a statewide scale is a fundamental step toward improving management of California's groundwater resources. The CASGEM program relies and builds upon the many previously established local long-term groundwater monitoring and management programs. Click here for the CASEGEM Data and Resources directory from the Department of Water Resources.